GRID-TIED BATTERY-BASED HYDRO-ELECTRIC SYSTEM Using batteries with your grid-tied system allows it to operate when the utility grid doesn’t. This type of system is the same as an off-grid system, except that the inverter needs to be designed and approved for grid-tied operation, so it can feed excess electricity into the utility lines. The dump load is only activated in the event of a grid failure, to protect the batteries from overcharging.